Consider the realm overlap between this world and theirs in the early days of the stories.
The internal time could be synced with ours and the torture is a collage of memes and mind worms and media of the worst kind - sweating to the oldies - endless dialogue from media corporate offices - muzak - Barney - Teletubbies - Shamwow

They fought Kore. The unstoppable scourge. And got him to stumble away.

But they nearly died doing it. The golem is expended. And they're not there to fight Kore in the first place. They start out just trying to get home from the war camp to the village. Right now they're trying to survive the dungeon crawl, maybe find Kin, and, oh yeah, save their entire plane of existence from being sucked into Hell. They've only got a few scattered hints about Kore's connection to the Axe and The Sacred. They're low on HP, we don't know how much more healing SVK has, and they just got a shockingly unexpected opportunity to talk to the ghost of their beloved friend. Focusing on Chief is the right call, and I'm not surprised they didn't notice Kore slipping away.

But now Chief has given them a quest to save him from the torture he's experiencing and, when they have a moment to catch their breath, Ears might be able to piece together Kore having mentioned being a Greyhill paladin. They'll have to chase him down. They just need a moment to grieve.

If I got a chance to talk to a much beloved dead friend, I would surely be distracted.

Further, people who make mistakes are more human and interesting.

Finally, it didn't take very LONG for them to notice that Kore had exited, stage left. Given that Kore just finished killing two of them, and survived having half his skull ripped off, I can't blame them for not giving chase. I wouldn't.

My problem is not that they didn't notice that Kore was escaping or that they want to talk to Chief. It's that they don't really react to it. He caused them so much grief, a desire to kill him from one of the Goblin would have been nice.

They were running scared from Kore. Chief sacrificed his life so they could run. They turned back to to to fight Kore with the Axe and the rope. He kept coming. They realized they were outclassed and ran. Forgath (as far as they know) sacrificed his life so they could run into the dungeon because that was safer than trying to fight Kore. The Axe broke, unleashing Hell on Earth Thuntonia*. They fought a demon and barely survived. They're still running through a dungeon with who knows what traps. Kore caught up to them and came within a hair of killing them all. Two of them were in negative hit points before Fumbles managed to heal them, but that's probably a once-a-day power. And then Kore summoned Chief's ghost, giving them roughly a minute to talk to him.

They've been either fighting or running from Kore this whole time. The entire world is being sucked into Hell and they're the only ones with a chance to fix it. They're low on HP, the golem is out of uses, and they only have a precious minute to talk to their dead friend.

They're going after Kore. But forgive them if shock, grief, and fatigue briefly overshadow their anger.

*Yes, it's still Thuntonia. Elli says she actually likes the name for the realm now because it's no longer named for her. She was never comfortable with having a world named after her, but now that's not her name so it's okay.

I can understand that they don't give two flying flacks where Kore goes. I react to the tone of it. We don't get a closeup frame of Kore in the foreground, glaring back as he walks off, declaring his ill intent. No. Last we see of Kore it looks like he is just standing there. Feet parallel. In a cut away frame. It looks like he is standing in the naughty corner. His head is glowing like a light bulb. His movement makes a terrible racket. Even the "camera" is really far back, giving us a wide shot like often used in comedic movies. Fumbles drops a little line of "Err, he is like going... away?" and noone gives a shit.

I really like it. It's some situational humour. One plot-line is dropped like an anvil for another, and no character seems bothered by it. We've seen time and time again really gritty dark stuff being mixed with goofy comedy. This time it's a framing comedy. Provided by someone else than MinMax/Boast and Fumbles.
Thumbs up.

I see it more as focusing on Chief's momentary return while Kore temporarily fades into the background.

As for Kore's departure, I see him taking weary heavy strides, head down, leaving behind a trail of blood, as he slinks off from unaccustomed defeat.

He's had a pretty rough week, too, come to that. Had a rope permanently fused with whatever is left of his windpipe, took a couple of good hits from Forgath, been dropped off a cliff, pummeled by a stone golem, had his head ripped open... Oh yes, and the Axe he helped forge is broken and the world he's been trying to save (in his own twisted way) for thousands of years is going to Hell.